boost::text::v1::at_grapheme_break
// In header: <boost/text/grapheme_break.hpp> template<code_point_range R> bool at_grapheme_break(R && r, std::ranges::iterator_t< R > it);
Returns true iff it is at the beginning of a grapheme, or it == std::ranges::end(range).
it
it == std::ranges::end(range)
